The abstract of the paper reads, “Compared with traditional stimuli-responsive devices with simple planar or tubular geometries, 3D printed stimuli-responsive devices not only intimately meet the requirement of complicated shapes at macrolevel but also satisfy various conformation changes triggered by external stimuli at the microscopic scale. However, their development is limited by the lack of 3D printing functional materials. This paper demonstrates the 3D printing of photoresponsive shape memory devices through combining fused deposition modeling printing technology and photoresponsive shape memory composites based on shape memory polymers and carbon black with high photothermal conversion efficiency. External illumination triggers the shape recovery of 3D printed devices from the temporary shape to the original shape. The effect of materials thickness and light density on the shape memory behavior of 3D printed devices is quantified and calculated. Remarkably, sunlight also triggers the shape memory behavior of these 3D printed devices. This facile printing strategy would provide tremendous opportunities for the design and fabrication of biomimetic smart devices and soft robotics.”
An FDM 3D printing method was utilized to create a 3D printed sunflower, which was able to mimic the plant family’s natural heliotropism (motion of plant parts in response to the sun’s direction) in order to demonstrate the new composite’s memory response.
“When materials comprising these photoresponsive groups are used to fabricate 3D printable photoresponsive devices through photopolymerization, the aforementioned transitions in the 3D printing process can lead to remarkable changes in the optical, mechanical, and chemical properties of the photoresponsive devices,” the researchers state in the paper.
The research team also used luminous triggers, because they can be accurately and easily focused, they’re fast, and they are able to be activated remotely. Once the photoresponsive, 3D printed sunflower was exposed to a xenon lamp or natural sunlight, it bloomed in less than five minutes.
According to the researchers, there aren’t too many stimuli-responsive 3D printed devices available, because there aren’t a lot of functional materials that are 3D printable. In addition, most of the existing devices only respond to temperature changes – not many react to other stimuli like chemical changes, humidity, and light. So, designing and creating 3D printable devices that are responsive to other types of stimuli could have a major impact in medical devices, soft robotics, and customized wearable sensors.
As the paper states, “these 3D printed stimuli-responsive devices may shape the future trends and opportunities of device development in various fields ranging from biomedical devices to soft robots.”
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[Source: Chemistry World / Images: Nanyang Technological University]